Permafrost degradation induced thaw settlement susceptibility research and potential risk analysis in the Qinghai-Tibet Plateau

With climate warming, numerous thaw settlements have occurred in the Qinghai-Tibet Plateau (QTP), but their possible distributions and potential risks are still poorly understood. The present study tends to come up with the first hazard data-driven thaw settlement susceptibility map for the QTP, and identify hazard-prone regions for settlement population, main infrastructures, and soil organic carbon (SOC). A well reliable susceptibility map was developed based on 111,510 thaw settlement sites and 12 conditioning factors using random forest (RF) model, logistic regression-based gradient boosting decision tree (GBDT-LR) model, and frequency ratio (FR) model. We found that nearly 120 thousand people, 1653 km of highway, 650 km of railway, and 3.13 Pg of the SOC were located in high and very high susceptible regions, which occupied 34.60% of the permafrost domain in the QTP. Alarmingly, the situation of Qinghai-Tibet Highway (QTH) and Qinghai-Tibet Railway (QTR) in permafrost regions seems more serious, more than 60% of them were located in high and very high susceptible regions. Our results revealed that slope aspect, volume ice content, and active layer thickness contributed significantly to the occurrence of thaw settlement. Compared with similar studies, this research performed better in model construction and accuracy. The results can provide references for decision maker in eco-environment protection and hazard risk management.